How-to prevent download of video files stored in SharePoint Online site

Context

• Event portal with both company internal as external audience
• Teaser videos to prepare the audience for the event
• Due the company information in the videos, not allowed that visitors download the videos for uncontrolled distribution.

An answer on the first aspect can be a SharePoint Online communication site, via Azure AD B2B external shared with known guest accounts. For the second aspect it would be preferred to use Microsoft Stream as secure Enterprise Video Platform. However, as Stream is still lacking the capability of external access; this would result that the external audience cannot watch the videos. Pragmatic alternative is then to fallback on using SharePoint Online itself as administration plus platform for the teaser videos. Remaining question is then whether possible, and if so how, to prevent that the external audience can easily download the video files.

Prevent download on SharePoint level

First component in answerring is to prevent on SharePoint Level that site visitors can download content from the site. The standard 'Read' permission level grants the authorization to "Can view pages and list items and download documents". There required to create a restricted permission level that only allows to "View content", and assign that permission level to the 'Visitors' permission group.

Prevent download on browser level

However, this does not prevent that visitors can download on browser level the SharePoint stored .mp4 videos, whether embedded in a SharePoint page, or the .mp4 video direct visited + played in the browser. All modern browsers native understand / recognize .mp4 as a video file, and then default to allow play, download and 'save as video' on browser level of that video file.

Does this mean it is not possible to prevent download of video files? The honest answer is: you can't stop downloading of html5 videos. But you can make the action more complicate to do. Multiple options for that.

Option 1: Download as blob in video player

This suggestion is made in Prevent HTML5 video from being downloaded (right-click saved)?

Result wrt default browser behavior:
As for the video player it is not .mp4, the default menu options for 'save as video' and 'download' are not triggered. However, on network level the video file is still initial downloaded as .mp4; and a knowledgeable person has no problem to simple direct navigate on browser level to the SharePoint address of the .mp4 videofile.

Option 2: Play as 'renamed video extension' file, so that default browser behaviour is prevented

Steps:

1. Rename the file extension to something else than .mp4; example rename 'SampleVideo.mp4' into 'SampleVideo.videofile'
2. Upload the renamed file into SharePoint Assets library
3. Also upload an image to use as preview
4. Embed a videojs based videoplayer on SharePoint page, that is configured to understand how-to play '.videofile' as '.mp4'. Also customize the videoplayer to not render the standard contextmenu

Result wrt default browser behavior:
As the file-extension is not a video format; neither SharePoint, nor browser recognize this as video file. And the default browser behavior to play the video-file address as video, is not fired; and thus the option from menus to ‘download’ + ‘save video as’ is not presented.

However, when navigating in browser to the SharePoint address of the renamed videofile, it will then download as file (despite that SharePoint permission does not allow). It is downloaded with the renamed file extension, but a knowledgeable person can guess that it is actual a .mp4 file, fix the downloaded file, and then it is native playable again.

Option 3: Convert from single .mp4 into HLS; with division accross multiple files

Steps:

1. Convert .mp4 video file into .HLS video (manifest file + video fragments). An approach for this is via 'FFmpeg'.
2. Upload the manifest + video fragments into SharePoint Assets library
3. Also upload an image to use as preview
4. Embed a HLS videoplayer on SharePoint page.

Result wrt default browser behavior:
Browser default do not handle HLS video files; this is handled via a HLS video player (JavaScript). To download the video, one must navigate in browser first to manifest file, and then all individual video fragments. Doable, but manual labor for the person downloading.